The present invention relates to safety systems for marine vessels, for example to safety systems for marine vessels operable to employ digital anchors to actively maintain the vessels in position in marine environments. Moreover, the present invention also relates to methods of providing such safety systems. Furthermore, the present invention also concerns software products executable on computing hardware for implementing such safety systems.
Apparatus for maintaining a marine vessel, for example a boat, in a desired position in a marine environment are known. In a simplest implementation, such apparatus is implemented as a mechanical anchor coupled by rope and/or chain either directly to the vessel, or via a winch arrangement to the vessel. This simplest implementation is useful in situations wherein water depth is not excessive, a sea or lake bed is of nature that the anchor can reliably grip onto the bed, and there is sufficient time or desire to deploy the anchor. More recently, it has been found beneficial to implement the apparatus actively wherein a desired position is maintained by actively propelling the vessel to the desired position determined by way of an absolute reference, for example Global Positioning System (GPS); the active implementation of the apparatus is conveniently referred to as being a “digital anchor”. Digital anchoring is employed in large marine vessels, for example oil drilling and production platforms for maintaining their drilling or wellhead positions accurately, as well as in small boats such as fishing boats.
In a published U.S. Pat. No. 5,386,368, there is described an apparatus for maintaining a marine vessel, for example a boat, in a desired position. The apparatus includes an electric trolling motor disposed to produce a thrust to pull the vessel, a steering motor disposed to affect the orientation of the electric trolling motor, a position deviation detection unit, and a control circuit. The position deviation detection unit is operable to detect a deviation in the position of the marine vessel from the desired position and also to transmit signals indicative of a deviation distance and a return heading to the control circuit; the “deviation distance” is defined as the distance from the marine vessel to the desired position, and the “return heading” is defined as the direction of the desired position from the marine vessel. The control circuit is operable to cause the steering motor to steer the electric trolling motor in a return heading in order to return the marine vessel to the desired position. In a first implementation of the apparatus described, the position deviation detection unit detects a deviation in position of the marine vessel based on GPS signals. Alternatively, in a second implementation, the position deviation detection unit detects a deviation in position of the marine vessel based on signals received from an anchored transmitter, for example provided from transmitters located in one or more buoys. Yet alternatively, in a third implementation, the position deviation detection unit detects a deviation is position based on forces caused by surrounding water when the marine vessel drifts.
In an international PCT patent application no. PCT/US95/04807 (WO 95/28682), there is described an anchorless boat positioning system which is operable to dynamically and automatically maintain a boat at a selected anchoring location within water without using a conventional anchor; the positioning system employs a steerable thruster whose thrust and steering direction are determined on the basis of position information signals received from GPS satellites and heading indication signals generated by a magnetic compass. The anchorless positioning system is operable to continuously monitor the position and heading of the boat and to compare the position and heading with stored coordinates of the selected anchoring location to generate control signals for controlling the steerable motor.
Whereas conventional mechanical anchors are susceptible to losing their spatial position in a marine environment by way of unsatisfactory gip to a sea or lake bed, digital anchors are susceptible to also losing accuracy in, for example, one or more of the following circumstances:
(a) a GPS reference becomes unreliable, for example adverse weather conditions degrade or interrupt GPS signal reception from GPS satellites;
(b) a GPS receiver failure occurs or an associated propulsion arrangement becomes unreliable, for example an engine stalls or a rudder becomes jammed in a given position; and
(c) a control system failure occurs, wherein the control system which is normally operable to drive an error between a desired position of the marine vessel within the marine environment relative to the measured GPS spatial position of the vessel to substantially zero is subject to failure, for example a computer system crashes and needs to be restarted.
Failure of digital anchors is thus susceptible to resulting in potentially dangerous situations, for example a person sails alone in a mariner vessel equipped with a digital anchor and then subsequently activates the anchor at a given location whilst temporarily leaving the marine vessel, for example for deploying fishing nets or for performing an off-boat task such as diving reconnaissance. In such a situation, the marine vessel is potentially unmanned such that failure of the digital anchor risks leaving the person stranded far out at sea. A conventional approach to reduce a risk of such failure is to improve integrity of the digital anchor, for example by duplicating or triplicating critical functional components of the digital anchor, or to employ a conventional anchor.
Thus, a technical problem addressed by aspects of the present invention is to improve operating safety of digital anchors, for example in a situation wherein a marine vessel is unmanned whilst its digital anchor is invoked into operation.
It is desirable to provide a safety system for marine vessels which is susceptible to improving user-safety of digital anchors.
According to a first aspect of the present invention, there is provided a safety system for a marine vessel, the vessel including one or more engines coupled to one or more propellers for propelling the vessel through water, and the vessel being provided with a digital anchor in communication with the one or more engines for maintaining the vessel substantially at a defined location when the anchor is activated,
characterized in that
the safety system includes a sensor assembly coupled to a data processing assembly for sensing a region of the water at least partially surrounding the vessel for detection of one or more persons present in the region and for modifying operation of the digital anchor is response to the one or more persons being detected.
The invention is of advantage, in an aspect thereof, in that the digital anchor is capable of responding to the one or more persons being present in the water and thereby reducing a risk of injury or loss of life when the digital anchor is employed.
Optionally, in the safety system, the system is operable to respond to the detection of the one or more persons by one or more of:
(a) deactivating the digital anchor;
(b) operating the engines so as to maintain the vessel in a proximity of the one or more persons;
(c) deactivating drive to the engines in an event that the one or more persons are closer to the propellers than a threshold distance.
Thus, the safety system is capable of reducing injury to the one or more persons by way of propellers of the vessel being driven to implement a digital anchor function in a more appropriate manner.
Optionally, in the safety system, the sensor assembly includes one or more infra red sensors for detecting infra red radiation generated by the one or more persons when present in the region of the water. Infra red sensors are of benefit in that they are capable of providing a most reliable signal indicative of a presence of the one or more persons in the region of the water.
More optionally, in the safety system, each of the one or more infra red sensors are scanned and/or pixellated image sensors operable to generate an output signal (Ci,j) for receipt at the data processing assembly representative of a spatial image of at least a portion of the region of water. Employing pixellated sensors provides the one or more sensors with spatial discrimination which is beneficial for more reliably detecting the presence of the one or more persons in the region of the water.
Optionally, in order to exclude interfering extraneous radiation at a human visible portion of the electromagnetic spectrum when employing the safety system, the one or more sensors are responsive in an electromagnetic radiation wavelength range of substantially 10 μm to 800 μm, more preferably in a wavelength range of 5 μm to 1 μm.
Optionally, to remove angular motion of the vessel from adversely affecting detection of the one or more persons in the region of the water, one or more sensors in the safety system are angularly stabilized for rendering the output signal (Ci, j) compensated for angular movement of the vessel relative to the water.
More optionally, in the safety system, the one or more sensors are mounted on one or more gyroscopically angularly stabilized servo-platforms in order to remove affects of angular motion of the vessel relative to the water from the aforesaid output signal (Ci, j).
Optionally, in the safety system, the data processing assembly is provided with computing hardware for computing a moving average for each spatial region of the image and for detecting differences in the moving average for detecting the presence of the one or more persons within the region of water. Computation of a moving average is a most reliable approach to detecting a presence of the one or more persons in the water in comparison to neural network-type detection or template comparison detection which are also within the scope of the present invention.
More optionally, in the safety system, the differences are compared with a threshold value for determining detection of the one or more persons in the region of water.
Optionally, in the safety system, the processing assembly is operable to compute the moving average with spatial averaging and/or temporal averaging which is varied in response to one or more of:
(a) solar irradiation onto the vessel and the region of water surrounding the vessel; (b) amplitude of wave motion in the region of water;
(c) wind speed at the vessel; and
(d) temperature of the region of water.
Modifying operation of the safety system in response to prevailing weather conditions is potentially capable of increasing reliability of detection of the one or more persons in the water.
More optionally, in the safety system, the processing assembly is operable to vary the threshold value in response to one or more of:
(a) solar irradiation onto the vessel and the region of water surrounding the vessel;
(b) amplitude of wave motion in the region of water;
(c) wind speed at the vessel; and
(d) temperature of the region of water.
In order to provide greater detection contrast relative to the water, in the safety system, each of the one or more persons are provided with one or more pulsed infra red sources attached thereto, the pulsed infra red sources being operable in water to emit pulsed infra red radiation bearing a signature code which is detectable at the one or more sensors and subsequently correlatable at the signal processing assembly to provide for more reliable detection of the one or more persons present in the region of water.
More optionally, in the safety system, the one or more pulsed infra red sources are automatically activated in response to contact with the water.
According to a second aspect of the present invention, there is provided a life vest attachable to a person, the vest for use with the safety system pursuant to the first aspect of the invention, the vest including one or more pulsed infra red sources attached thereto, the pulsed infra red sources being operable in water to emit pulsed infra red radiation bearing a signature code which is correlated at the signal processing assembly to provide for more reliable detection of the one or more persons present in the region of water.
According to a third aspect of the present invention, there is provided a head assembly attachable to a person, the head assembly for use with the safety system pursuant to the first aspect of the invention, the head assembly including one or more pulsed infra red sources attached thereto, the pulsed infra red sources being operable in water to emit pulsed infra red radiation bearing a signature code which is correlated at the signal processing assembly to provide for more reliable detection of the one or more persons present in the region of water.
According to a fourth aspect of the invention, there is provided a method of detecting one or more persons present in a region of water at least partially surrounding a vessel, the vessel including one or more engines coupled to one or more propellers for propelling the vessel through water, and the vessel being provided with a digital anchor in communication with the one or more engines for maintaining the vessel substantially at a defined location when the anchor is activated,
characterized in that the method includes steps of:
(a) using a sensor assembly coupled to a data processing assembly for sensing the region of the water for detecting one or more persons present in the region; and
(b) modifying operation of the digital anchor in response to the one or more persons being detected by the data processing assembly.
Optionally, the method includes a step of responding to the detection of the one or more persons by one or more of:
(a) deactivating the digital anchor;
(b) operating the engines so as to maintain the vessel in a proximity of the one or more persons; and
(c) deactivating drive to the engines in an event that the one or more persons are closer to the propellers than a threshold distance.
Optionally, in the method, the sensor assembly includes one or more infra red sensors for detecting infra red radiation generated by the one or more persons when present in the region of the water.
Optionally, in the method, each of the one or more infra red sensors are scanned and/or pixellated image sensors operable to generate an output signal (Ci, j) for receipt at the data processing assembly representative of a spatial image of at least a portion of the region of water.
More optionally, in the method, the one or more sensors are responsive in an electromagnetic radiation wavelength range of substantially 10 μm to 800 nm, more preferably in an electromagnetic wavelength range of 5 μm to 1 μm.
Optionally, in the method, the one or more sensors are angularly stabilized for rendering the output signal (Ci, j) compensated for angular movement of the vessel relative to the water.
Optionally, in the method, the one or more sensors are mounted on one or more gyroscopically angularly stabilized servo-platforms for compensating in the output signal for angular movement of the vessel relative to the water.
Optionally, in the method, the data processing assembly is provided with computing hardware for computing a moving average for each spatial region of the image and for detecting differences in the moving average for detecting the presence of the one or more persons within the region of water.
More optionally, in the method, the differences are compared with a threshold value for determining detection of the one or more persons in the region of water.
Yet more optionally, in the method, the processing assembly is operable to compute the moving average with spatial averaging and/or temporal averaging which is varied in response to one or more of:
(a) solar irradiation onto the vessel and the region of water surrounding the vessel;
(b) amplitude of wave motion in the region of water;
(c) wind speed at the vessel; and
(d) temperature of the region of water.
Yet more optionally, in the method, the processing assembly is operable to vary the threshold value in response to one or more of:
(a) solar irradiation onto the vessel and the region of water surrounding the vessel;
(b) amplitude of wave motion in the region of water;
(c) wind speed at the vessel; and
(d) temperature of the region of water.
Optionally, to further enhance operation of the method, the method includes steps of:
(a) providing each of the one or more persons with one or more pulsed infra red sources attached thereto, the pulsed infra red sources being operable in water to emit pulsed infra red radiation bearing a signature code detectable at the one or more sensors; and
(b) correlating at the signal processing assembly the received signature code received from the one or more pulsed infra red sources to provide for more reliable detection of the one or more persons present in the region of water.
More optionally, in the method, the one or more pulsed infra red sources are automatically activated in response to contact with the water.
According to a fifth aspect of the invention, there is provided a software product executable on computing hardware to implement a method pursuant to the fourth aspect of the invention.
It will be appreciated that features of the invention are susceptible to being combined in any combination without departing from the scope of the invention as defined by the accompany claims.
In the accompanying diagrams, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.